Method of securing light fastness in transfer copies



Patented July 27, 1937 UNITED STATES PATENT. orrl'cs METHOD or sscunme mon'r FASTNESS m TRANSFER corms William Hoskins, -Jr., La- Grange, lll., assignor to Ditto, Inco p rated, Chicago, 111., a corporation of West Virginia -No Drawing. Application May 23, 1936, Serial N0. 81,514

a can... (Cl. 41-315) 1 The present invention relates to improvements in transfer processes for effecting reproduction or transfer of designs, drawings, written and typewritten material and the like from an orig- 5 incl or master copy and more particularly to a process of making transfer copies resistant to moisture and of great fastness to light.

In certain of the transfer or reproduction sheets to the copy mass, each receiving a proportion of the dye or coloring matter to form a copy of the design or writing on the master sheet.

In another reproduction process, the master 25 copy is prepared in reverse by drawing, writing,

typing or otherwise producing the design on a master sheet, behind which is a sheet of suitably prepared color-carrying paper with its inked surface facing the master sheet, so thatcolor a constituents of the ink on the carbon paper are transferredto the back of the sheet, forming a reverse copy of the design or writing. In preparing copies from this master sheet, the surface of the copy sheet is moistened with a liquid, 85 usually a water-miscible alcoholic liquid, which has a solvent action on the dyes in the ink deposited on the master sheet from the carbon paper, and the moistened copy sheets are applied to the back of the'master sheet, a positive image of the original being thereby reproduced upon the copy sheet. In carrying out such processes, aqueous andalcohol soluble dyes are generally used in the color-carrying P per and hence aqueous and alcoholic solvents have been employed to effect the transfer,

-In view of the fact that water and alcohol soluble dyes are generally employed in such transfer processes, the character of the colors" 50 available for use therein has been seriously limited in many directions; for example, by lack of moisture resistance and by lack of fastness to light. Due to the water-soluble character ofthe dyes'employedthe fingers of the users of the 66 paper have been soiled by contact therewithv and water resistance the impressions on the copy sheets have been blurred and smudged on handling. In accordance with the present invention, the water and alcohol soluble dyes may be advantageously employed in the transfer processes, and increased water resistance and with increased fastness to light may be secured in the copies. Thus the water and alcohol soluble dyes .used in the transfer processes, such as methyl violet, crystal violet, fuchsines, magentas, 1o anthraquinones, chrysoidine and the like; the .water and alcohol soluble aniline dyes, such as aniline blue, Victoria blue and orange, Nile blue and the like; the water and alcohol soluble azo dyes, such as Congo red, Bismarck brown and the, like, may be advantageously used in these processes and copies may be secured on greatly increased fastness to light and water-resistance. I

I have found that these desired properties may be advantageously imparted to the water and alcohol soluble dyes used in the transfer processes by contacting the color impressions on the copy sheets with a colloidal material adapted to combine with, the colors or-dyes to render them substantially water-insoluble and fast to light. Thus I have found, for example, that the' highly colloidal clays such as bentonite will react on and with the water and alcohol soluble dyes to increase their fastness to light for a given strength of copy'and to renderthem substan- 'tially water resistant. While I am not able to fully explain the reason for this phenomenon, it appears that the dyes are adsorbed by the colloidal particles of the bentonite to form what appears to be a. lake having less fugitiveness than the original dye.

. In"= carrying out the present invention, it is l essential that the colloidal material such as bentonite be available for contact with the dye transferred to the copy sheet. Thus, the ben- 40 toiiite can be incorporated into the copy paper either with the size or filler compositions; or may be applied to the copy paper having the transfer impression thereon, as a surface wash; I or may be incorporated with the paper as part of a surface coating or glaze in preparingit for use in the transfer process. In each of these methods, the bentonite is available to contact the dye on the copy paper and react thereon or therewith to reduce its fugitiveness, increase its and render it more fast to light. As illustrative of one method of incorporating the bentonite" into the copy .paper the following is set forth. howeveifit is to be understood-that as any of the methods set forth above or methods equivalent thereto may be employed with substantially equ l advantage.

Thus, with any. of the known conventional ly disperse the size and bentonite throughout processes of the type hereinbefore referred to,

the pulp. The pulp is then treated in the usual manner to form a sheet suitable for use as copy paper. 0r preferably, in connection with a tub size of the usual character, the bentonite may be incorporated to theextent of 1% to 7% and preferably 2% to about 5% or even higher. of.

course, if desired, a suspension of bentonite in rate coating or wash on the copy paper. If desired, small amounts of hygroscopic substances such as glycen'ne, dextrine, invert sugar or the like in the order of say from 0.1% to 1% may be incorporated with the size composition containing bentonite. These hygroscopic substances prevent the excessive drying out of the sizing composition and thus prevent the loss of bentonite from the paper.

As indicated above, proportions of bentonite greater than 5 to 7% may be employed; how-' ever, no enhanced result appears to flow from this increase in the percentage of bentonite. As very little dye isactually transferred onto the copy paper, very little bentonite is actually needed and therefore the amount of -bentonite present to react with the transferred dye on the copy paper should be suflicient to produce the desiredv results. In actual practice, I have found that from 0.5 to 5% of bentonite in the size' or surface wash is sufficient.

The copy paper or sheets prepared as hereinbefore described and having bentonite in minute proportions onthe copy surface is then employed to receive the copies. in the transfer the prepared copy paper being, for example, applied to a hectographic copy masscarrying reverse ink impresions or being moistened and applied toa reverse master copy.

The dye transferred to the copy sheet coac with the bentonite available therein and the' dye is thus rendered water-resistant and of increased fastness to light. Copy sheets having a design reproduced thereon according to my process can be readily handled without soiling the fingers of the users and without smudging and blurring -of the impressions, and do not rapidly fade or lose strength or brilliance on exposure to light as with copies of similar under running water without affecting the color or causing bleeding or of the color. As pointed out-hereinabove, by operating in accordance with the present invention it is possible to-secure, in the copy sheets, colors having characteristics not hitherto secured in such processes employing water-soluble and alcoholsoluble dyes for reproduction purposes, and

' particularly colors having an increased water resistance and an increased fastness to light.

I claim:

1. The process of reproduction of designs formed from water and alcohol-soluble dyes to render the dyes in the reproduced design moisture resistant and fast to light which comprises applying a copysheet containing available benitonite on its surface to a surface having a design formed thereon from water or alcoholsoluble dyes and thereby transferring. a portion of the dye to said copy sheet to form the design thereon, whereby the dye and bentonite coact to render the dye on the copy sheet moisture resistant and fast to light. 7

2. The process of reproducing color designs to form color designs having an increased fastness to light which comprises contacting a copy sheet containing available bentonite on its surface to a surface having a design formed thereon from water or alcohol-soluble dyes and thereby transferring a portion of the dye to said copy sheet to form the design thereon, whereby the dye and bentonite coact to render the dye on the copy sheet moisture resistant and fast to light. 3. The process of reproducing color designs to containing a small quantity of bentonite uniformly applied on the surface of the sheet to a surface having a design formed thereon from water or alcohol-soluble dyes and thereby transferring a portion of the dye to said copy sheet to form the design thereon, whereby the dye! and bentonite coact to render the dye on the copy sheet moisture resistant and fast to light.

4. The process of reproducing color designs vto form color designs having an increased fastness to light whichgcomprises applying to a master sheet a water or alcohol soluble dye to forma design in reverse, moistening a copy sheet containing bentonite with a solvent and applying the moistened copy sheet to the side of the master sheet bearing said dye, thereby transferring a portion ofthe dye tosaid copy sheet to form thedesign thereon,'whereby the dye and bentonite coact to render the dye on the copy sheet moisture resistantand fast to li ht.

5. Inc process of reproducing color designs in a hectograph process to form color designs having an increased fastness to light .which comprises applying .to a sheet .a water or alcohol soluble dye to form a design thereon, contacting the design on said sheet with a copy pad to) transfer the design in reverse to said pad, and

contacting a copy sheet containing available bentonite on its surface with the copy pad to transfer the design to said copy sheet, whereby thedye and bentonite coact to render the dye on the copy sheet moisture resistant and fast to light.

' 'WHLTAM HOSKmS, JR. 

